Ticket #31643: 31634.diff

src/wp-admin/widgets.php

@@ -413 +413 @@
 <?php
 
 foreach ( $theme_sidebars as $sidebar => $registered_sidebar ) {
-        $wrap_class = 'widgets-holder-wrap';
-        if ( !empty( $registered_sidebar['class'] ) )
-                $wrap_class .= ' sidebar-' . $registered_sidebar['class'];
+        $wrap_class = array(
+                'widgets-holder-wrap'
+        );
+        if ( !empty( $registered_sidebar['class'] ) ) {
+                $wrap_class[] = ' sidebar-' . $registered_sidebar['class'];
+        }
 
-        if ( $i > 0 )
-                $wrap_class .= ' closed';
+        if ( $i > 0 ) {
+                $wrap_class[] = 'closed';
+        }
 
+        $wrap_class = join( ' ', apply_filters( 'registered_sidebar_wrap_class', $wrap_class, $i, $theme_sidebars, $sidebar, $registered_sidebar ) );
+
         if ( $split && $i == $split ) {
                 ?>
                 </div><div class="sidebars-column-2">